A liquid flow rate control valve for carrying out PWM control of the flow rate of a liquid is known from Patent Document 1 below. With regard to this liquid flow rate control valve, a cylindrical valve plate 40 having left and right edge parts formed into a wave shape is disposed in the interior of an outer tube 10 having one input port 11 and two, that is, first and second, output ports 12 and 13 so that the cylindrical valve plate 40 can be rotated by a drive source, a control plate 50 having a plurality of first and second opening groups 41 and 42 is disposed between an outer peripheral face of the valve plate 40 and an inner peripheral face of the outer tube 10 so that the control plate 50 can be moved in the axial direction by a drive source, and a liquid supplied from the input port 11 of the outer tube 10 is made to pass through the first and second opening groups 41 and 42 of the control plate 50 and the left and right wave-shaped edge parts of the valve plate 40 and be discharged from the first and second output ports 12 and 13 of the outer tube 10. In this process, changing the period during which the first and second opening groups 41 and 42 of the control plate 50 are open and the period during which they are closed by the left and right wave-shaped edge parts of the rotating valve plate 40 in response to the axial position of the control plate 50 enables the duty ratio of liquid discharged from the first and second output ports 12 and 13 to be freely controlled, and changing the rotational speed of the valve plate 40 enables the duty frequency of liquid discharged from the first and second output ports 12 and 13 to be freely controlled.    Patent Document 1: Japanese Patent Application Laid-open No. 2009-68553